Device for regulating and cleaning an air intake

ABSTRACT

A device for regulating and cleaning an air port ( 3 ) arranged in the wall ( 2 ) of a furnace, especially a soda house furnace, comprises a cleaning arrangement ( 1 ) and an arrangement ( 4 ) for regulating the air flow through the air port, in which an air casing ( 5 ) is arranged around the air port on the outer side of the furnace wall, in which a drum ( 12 ) is arranged inside the air casing and air-tightly connected to the wall of the air casing located opposite to the furnace wall. An opening defined by at least a cover member ( 14 ) of the regulating arrangement and at least one lateral wall of the drum is arranged with a restricted extension in the circumferential direction of the drum so as to achieve an air jet in towards and through the air port ( 3 ).

FIELD OF THE INVENTION AND PRIOR ART

The present invention relates to a device for regulating and cleaning anair port (3) arranged in a wall (2) of a furnace, especially a sodahouse furnace, comprising a cleaning arrangement (1), which in it turncomprises a cleaning member (7) movable with respect to the walls of theair port (3), and arrangement (4) for regulating the air flow throughthe air port (3), and air casing (5) being arranged around the air port(3) on the outer side of the furnace wall (2), a drum (12) beingarranged inside the air casing (5) and connected to a wall (13) of theair casing (5) located opposite to the furnace wall (2), the cleaningarrangement (1) being also connected to the wall (13) of the air casing(5) and extending at least partially through the drum (12), theregulating arrangement having a cover member (14) movable with respectto the drum (12), the cleaning member (7) being movable between two endpositions and independently of the position of the cover member (14),and the cleaning member (7) being in a first of the end positionslocated at least partially inside the furnace and a second of the endpositions at least partially outside the furnace.

Such devices are used within the field of soda house furnaces and thelike, in which the wall is provided with a plurality of air ports, theair flow of which has to be regulated and which sometimes have to becleaned.

Within the cellulose industry the spent liquors from paper wood boiling(sulphate spent liquor and in some case sulphite spent liquor) arecombusted for recovery in a recovery boiler. The nature of the fuel andthe process conditions result in a tendency of plugging of the openings,through which combustion air is supplied, usually called air ports,through dust particles and flowing cinder products. These pluggings aremore accentuated in the lower region of the air port and especially atthe bottom thereof. There are different arrangements of cleaning membersreciprocating in the air ports for cleaning thereof and which areactivated upon need or periodically. It is important from theenvironmental point of view to achieve such a complete combustion aspossible of the spent liquor located in the recovery boiler. The supplyof air is an important parameter for this purpose. A regulating deviceis arranged for regulating the air supply through an air port. There areaccording to the prior art a number of examples of regulating devicesand cleaning devices for furnace air ports.

According to a first example of the prior art the cleaning member has asleeve shape and has also a task to regulate the air flow, which isachieved by the fact that the sleeve has a cross section having a shapeand size corresponding to the air port, in which the air flow present ina slit between the cleaning member and the air port, which as such has acleaning effect, is dependent upon how far the cleaning member isintroduced into the air port in the resting position thereof. Such adevice has the advantage that air will be supplied without any control,or at least intermittently during the cleaning operation.

According to a further example of the prior art the cleaning member hasonly a cleaning function, and a throttle is arranged for regulating theair supply. The throttle is here arranged on the outer side of thefurnace wall close to the air port and may for example be constituted bya lid being moveable downwardly for covering the air port. When cleaningof the air port is to take place the lid has accordingly to be removedfrom the position thereof covering the air port at least partially, sothat the cleaning member may be introduced into the air port. Anuncontrolled flow of air into the air port during the cleaning thereofalso takes place in this example.

According to a further example of the prior art, the cleaning device isat least partially enclosed in a drum, which extends from a wall locatedopposite to the furnace wall and belonging to an air casing arrangedoutside the airport, said drum extending from said wall in the directiontowards the air port. The cleaning device is of a conventional type andcomprises a cleaning member, a holding element and a power member, inwhich the cleaning member is arranged at one end of the holding element,said holding element being at a second and thereof actively connected tothe power member, in which the cleaning member is moveable in areciprocating movement with respect to the air port for cleaning thewalls thereof. A sleeve is moveable along the length of the drum at anend thereof facing the air port. Said sleeve having an inner crosssection shape corresponding to the outer cross section shape of the drumso as to seal around the drum and an at least somewhat larger crosssection than the air port for also being able so seal therearound. Bysuch a design the cleaning member may be brought to and fro through theair port while the sleeve is arranged in a position causing a suitableair flow to the air port. The air will then flow through acircumferential slot formed between the sleeve and the furnace walllocated around the air port. As a consequence of the flow ofnon-combustible material and cinder products along an inner wall of thefurnace and the tendency thereof to cause pluggings of the air port thismay also reach the circumferential slot and at least partially plug it.Upon such a partially plugging of the slot air will flow in through theair port through portions of the slot not plugged, which on one handresults in a reduction of the controllability of the air flowing throughthe air port since changes of the position of the sleeve with respect tothe air have to be carried out with increasing degree of plugging, andon the other the non-combustible material reaching the slot mayimmobilise the sleeve or at least create a resistance against movementthereof. The plugging of the air port will primarily take place at thebottom of the air port, since the flowing non-combustible material iscollected on the bottom, which means that the immobilisation of thesleeve tends to take place of the portion of the sleeve intended tocover the bottom of the air port. As a consequence of the fact that theopening formed for the air flow is slot-like a comparatively shortmovement of the sleeve will result in a comparatively large change ofthe area of the opening, which means that a device with a high accuracyfor the movement of the sleeve is required for obtaining a changedesired of the amount of air flowing into the furnace per time unit.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a device forregulating and cleaning an air port arranged in the wall of a furnace,which eliminates at least some of the drawbacks mentioned above inregulating and cleaning an air port according the conventionaltechnique.

This object is according to the device according to the inventionobtained by arranging the cover member for regulating the air flowthrough at least an opening defined by at least a lateral wall of thedrum and having a restricted extension in the circumferential directionof the drum. By the fact that the at least one opening has a restrictedextension in the circumferential direction of the drum the opening willnot have any circumferential slot character, so that the problemsdefined above of an opening with a slot-shape are eliminated.

According to an embodiment, in which the cover member has at least awall portion for at least partially cover the opening on movement of thecover member and where the cover member is movable substantially in thelongitudinal direction of the opening, it is possible to make the shapeof the effective open area of the opening almost point-like, in whichthe air flowing through the opening and further into through the airport may have a substantially jet-like character. Such an air jet meansa higher degree of concentrated air amount with respect to the characterof the air flowing in through a slot-like opening according to the priorart, which involves a number of advantages. Firstly, it will be easierto check and regulate the air flow into the furnace, and an air flowinto the furnace being turbulent to a smaller extent is achieved due tothe air jet, which in its turn means that the air flowing in may reachfurther into the furnace and may by that in a higher degree preventparticles incompletely combusted to flow up from the melt in a centreregion of the furnace.

According to another embodiment of the invention, in which at least aportion of the opening is arranged on the level with a bottom of the airport, the air supply will in a higher degree take place along thisbottom, which in its turn means that a clean flushing of cinder productsfrom this bottom being stronger than in the prior art is achieved.

According to another embodiment of the invention, which constitutes afurther development of the preceding embodiment, an end of the drumfacing the air port is at least partially arranged at a distance fromthe furnace wall delimiting the air port, and an upper and a lower wallpart having an extension in the transversal direction of the drumsubstantially corresponding to the width of the drum is adapted toconnect the drum at the top and at the bottom, respectively, with theair port, which means that two openings oppositely located are formed inthe transversal direction of the drum and between the furnace walldelimiting the air port, a lateral wall arranged in the transversaldirection of the drum and said wall parts, respectively, and by the factthat the cover member has two substantially parallel wall portions whichare arranged at a mutual distance substantially corresponding to thewidth of the drum. The cover member will upon a movement in parallelwith the furnace wall delimiting the air port more or less cover theopenings formed between the surface wall delimiting the air port, thelateral walls of the drum and said wall parts. This means that the covermember in a rest position allowing air supply through the openings isarranged at a distance from the bottom of the air port, and it iscounteracted that the cover member gets stuck by possible cinderproducts gathered on the bottom of the air port.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the appended drawings, below follows a detaileddescription of preferred embodiments of the invention cited as examples.

In the drawings:

FIG. 1 shows a partially sectioned perspective view of the deviceaccording to the invention according to a first preferred embodiment.

FIG. 2 shows a partially sectioned lateral view of the device accordingto the invention, where the cover member is arranged in a firstposition, in which it totally covers openings formed between the drumthe furnace wall.

FIG. 3 is a partially sectioned lateral view of the device according tothe invention according to the first preferred embodiment, where thecover member is arranged in the second position, in which it formsopenings between the drum, the furnace wall and itself.

FIG. 4 is a perspective view of the cleaning arrangement in a positionremoved from the air casing.

FIG. 5 is a perspective view of the cleaning arrangement according tothe invention.

FIG. 6 shows the cleaning member in a position in which it's activefront cleaning element is arranged inside the air port.

FIG. 7 shows the cleaning member in a position in which the active frontcleaning element is arranged inside the furnace.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

A partially sectioned perspective view of the device according to theinvention according to a first preferred embodiment is illustrated inFIG. 1. The device comprises on one hand an arrangement 1 for cleaningan air port 3 arranged in a wall 2 of a furnace from dust particles andflowing cinder products from the interior of the furnace, and on theother an arrangement 4 for regulating the flow of air through the airport 3.

The furnace is especially a soda house furnace, and the device isespecially suited for regulating and cleaning air ports of such a sodahouse furnace, but also other applications are conceivable for thedevice according to the invention. Such a soda house furnace or recoveryboiler comprises a number of such air ports distributed around thefurnace wall above the level of the spent liquor located in the furnace.A first series of air ports are called primary air ports, and a secondand a third series of air ports on levels in a vertical direction abovethe first series are called secondary air ports and tertiary air ports,respectively, and so on. The device according to the invention isapplicable to any of these series of air ports. A regulating andcleaning device is arranged for each of the air ports.

On the outer side of the furnace wall 2 a closed so called air casing orcabinet 5 is arranged around the air port 3. This is in the case shownsecured to the furnace wall 2. The air casing 5 has an inlet 6 for hotair, which leaves the air casing through the air port 3 for combustionof the spent liquor inside the furnace. It is then possible that an aircasing is arranged for each air port or that one air casing enclosesseveral or even all the air ports arranged on a certain level around thefurnace. The air casing is suitably provided with an amount of airinlets.

The cleaning arrangement 1 comprises a cleaning member 7, a holdingelement 8 and a power member 9, said cleaning member being arranged atone end of the holding element, and the holding element is at a secondend actively connected to the power member. The cleaning member 7, whichwith respect to the shape corresponds to the air port 3 but to thedimension is slightly smaller than this, is moveable through the powermember 9 through two end positions, in which the cleaning member in afirst end position is located at least partially inside the furnace andin a second end position at least partially outside the furnace. Thecleaning member 7 is in FIG. 1 arranged with the active cleaningelements 10, 11 thereof inside the furnace. When the cleaning member 7is moved between said two end positions the cleaning elements will bebiased against at least the two walls arranged in the transversaldirection of the air port and by that remove dust particles and cinderproducts from the spent liquor deposited thereon. The power member isconstituted by a piston/cylinder assembly. The detail design andfunction of the cleaning member will be described more in detail inconnection with FIGS. 5-7.

An arrangement 4 for regulating the flow out through the air port 3comprises a drum 12, a cover member 14 and a regulating mechanism 15.The drum 12 is preferably substantially air-tightly connected to anouter wall 13 of the air casing located opposite to the air port 3.Parts of the regulating arrangement 1 extend through the drum 12.According to the first preferred embodiment of FIG. 1 the cover member14 is movable in the vertical direction by means of the regulatingmechanism 15. The regulating mechanism 15 has for this purpose a powermember 16. Also this power member is constituted by a piston/cylinderassembly.

It is by that possible to move the cleaning member by means of thedevice according to the invention independently of the position of thecover member 14 between said two end positions. This means that thecleaning of the air port may be carried out by means of the cleaningmember while the cover member is arranged in a determined position, inwhich it allows a controlled air flow desired in through the air port.By the fact that the cover member 14 not in any position covers any partof the air port as seen from the inside of the drum 12, it is possibleto look at the entire air port 3, and also look into the interior of thefurnace, at any time through a viewing window 17.

The drum 12 has a substantial rectangular cross section with asufficient height and width for being able to receive the cleaningmember 7 when this is retracted to a rear end position.

FIG. 2 illustrates the device according to the invention according toFIG. 1. The cover member 14 is arranged in a lower end position. Theregulating mechanism 15 for moving the cover member 14 in the verticaldirection has a lever 18, which at one end 19 thereof is pivotally andactively connected to a piston rod 23 of a power member 16 and at theother end 20 thereof is pivotally connected to a power transmittingpart. The lever 18 is also suspended in and pivotable around a point 22.The power transmitting part 21 is in its turn connected to the covermember 14. The power member 16 is constituted by a power cylinder, whichmay cause a movement in the vertical direction of the cover member 14 bydisplacing the piston rod 23 thereof through the lever 18 and the powertransmitting part 21. An upper portion 24 of the cover member 14embraces a vertical rod 25 and is slideably displaceable along this rod.The first end 19 of the lever 18 may by means of the power member 16 bemoved between two end positions. A circle sector-like part 26 extendingthrough the wall 13 of the air casing 5 has a slot for receiving thelever 18. The circle sector-like part has an arc angle being sufficientfor allowing a movement of the first end 19 of the lever between two endpositions corresponding to the two end positions of the cover member 14.The lever 18 is also air-tightly connected to the circle sector-likepart 26.

FIG. 3 illustrates the device, where the cover member 14 is located inan upper position. The cleaning member 7 is also arranged in the rearend position thereof. The movement of the cleaning member 7 betweenthese two end positions may take place independently of the position ofthe cover member 14. An upper wall part 27 having an extension in thetransversal direction of the drum 12 substantially corresponding to thewidth of the drum is arranged for connection of the drum at the top withthe furnace wall 2 delimiting the air port 3. Also the frame portionextending around the air port 3 in the direction towards the interior ofthe air casing 5 is comprised by the furnace wall 2. A lower lateralwall 28 of the drum 12 extends at least partially into the air port 3,in which the drum partially is carried of said frame portion, andreceives the control in the transversal direction thereof. By said upperwall part 27 and the lower wall part 29 extending from the lower lateralwall 28 the space located between the drum 12 and the air port 3 isdelimited upwardly and downwardly, respectively.

The cover member 14 has two substantially parallel wall portions 30, 31,which are arranged at a mutual distance substantially corresponding tothe width of the drum 12 so as to at least partially cover the openings32 located between the furnace wall 2 delimiting the air port, thelateral walls of the drum in the transversal direction and said wallparts 27, 29 when the cover member 14 is moved. When the cover member 14is moved from the position shown in FIG. 2 to the position shown in FIG.3 the openings 32 have an increasing efficient opening area. Therespective opening 32 has a shape causing a flow of air in through theair port 3 with the character of an air jet. Lower parts of wallportions 30, 31 of the cover member 14 are by that arranged at adistance in a vertical direction above the bottom 37 of the air port,when the cover member is arranged in a position allowing an air flowinto the air port.

The definition lateral wall of the drum as used above and in the claimsis intended to comprise walls in a transversal direction of the drum aswell as in the vertical direction thereof.

The drum 12 is secured, for example by a welded joint, to a first plate39, which is arranged on an outer side of the wall 13 arranged oppositeto the air port. The first plate 39 is connected to a second plate 40,which in its turn is releasably connected to the wall 13. The secondplate 40 has a hole for receiving the drum and is arranged around a holethrough the wall 13 of the air casing 5 also intended for receiving thedrum. The drum 12 will in an active position by that extend through boththe second plate and the wall 13. The second plate 40 is through forexample a screw joint connected to the wall 13. The first plate 39 maybe orientated with respect to the second plate 40 so as to allow acertain possibility to orientate the drum 12 in the air casing 5. Thispossibility to orientate is achieved by the fact that the first plate 39is connected to the second plate 40 through a screw/spring joint while asealing means 41 is arranged between the plates. By tightening thescrews of the screw/spring joint a desired orientation of the firstplate 39 with respect to the second plate 40 and by that a desiredorientation of the drum in the air casing may be obtained.

The cleaning member 7 is as mentioned above rigidly connected to aholding element 8, which in its turn is guided in a hollow beam member33 extending from a third plate 42. The third plate 42 is releasablyconnected to an outer side of the first plate 39 covering the lowerregion of a hole provided through said first plate, which holeconstitutes a prolongation of the inner space of the drum 12, so thatthe beam member 33 extends through the drum 12 in the direction towardsthe air port 3. Furthermore, the viewing window 17 is arranged above thethird plate 42 on the outer side of the first plate 39 covering an upperregion of the hole provided through the first plate. Furthermore, thethird plate 42 has a hole for receiving the holding element 8 and isprovided with an angle at the upper end thereof for making the viewingwindow to overlap the upper end, which results in a good covering of thehole of the first plate. The upper end of the third plate 42 is providedwith a lip 43, see also FIG. 4.

The driving member 9 of the cleaning arrangement 1 is in its turnrigidly connected to the third plate 42, and the holding element 7 ismovably received in the hole of the third plate 42.

It is important that the beam member 7 may be moved back to a positionat a comparatively great distance to the air port 3, see FIG. 3, sincethe temperature in the furnace is extremely high, approximately in theinterval 750-1100° C., and would the cleaning member 7 be arranged inthe rear resting position in a position in or in the immediate proximityof the air opening 3, the cleaning member would be excerted to severestresses and after some time be deformed and/or dissociated as aconsequence of the high temperature. However, the air flowing in throughthe opening 6 has a considerably lower temperature, for example in theinterval from 150-225° C., and the cleaning member 7 is cooled by thisair.

The piston rod 36 of the power member 9 is rigidly connected to theholding element 8. The holding element is in FIG. 3 reciprocatinglyreceived in a hole through the third plate 42. According to analternative, which is shown in FIGS. 1 and 2, the piston rod 36 isinstead reciprocatingly received in a hole made for this through thethird plate 42.

FIG. 4 illustrates the releasable connection of the cleaning arrangement1 to the outer wall 13 of the air casing described above. As aconsequence of the releasability it is easy to remove the cleaningarrangement from the air casing, which is important should for examplethe cleaning member fail. When the cleaning arrangement 1 is withdrawnfrom the air casing the viewing window 17 will be arranged in a positionpivoted upwardly. It is then easy to take out the drum 12 from the aircasing should this be desired thanks to the releasable connection of thesecond plate 42 to the outer wall 13 also described above.

The first preferred embodiment of the invention described above is onlyan example of a constructive design of the invention and the inventionmay accordingly be realised in a plurality of different ways whilemaintaining the basic inventional idea. It is in particular pointed outthat men with skill in the art may after gaining knowledge about thesolution according to the invention of course be able to carry outdifferent modifications of the embodiment described as an examplewithout departing from the scope of the patent protection.

The drum 12 may for example within the scope of the claims according tothe invention have a cross section being different than rectangular. Thefunction of the drum is to at least partially form at least an openingfor flowing of air in to the air port 3 and for the rest act sealinglyagainst flow of air in from the interior of the air casing 5, so thatthe flow of air into the air port 3 may be regulated by at leastpartially covering the opening by means of the covering member 14.

The opening intended for air flowing in and defined by at least onelateral wall of the drum is adapted to extend around more than half ofthe circumference of the drum. According to the first preferredembodiment of the invention two oppositely located openings arearranged, but also one, three or more openings are possible. By thearrangement of the cover member movable in the longitudinal direction ofthe opening an efficient opening area defined by at least the covermember 14 and at least a lateral wall of the drum may be formed by theopening with a shape being substantially different than a slot. Theeffective part of the opening is intended to have such a shape that theair flowing through the opening and further on towards the air port 3will form a concentrated shape, such as for example an air jet. Byarranging the opening/openings in close connection to the air port theair jet flowing through the opening will in a higher degree beconcentrated when it flows through the air port than should the openinghave been arranged at a greater distance to the air port.

As a consequence of the arrangement of the effective opening on a levelcorresponding to the lower region of the air port the air will flow outthrough the air port to a large extent in this lower region, and to asmall extent through an upper region of the air port, which means a highconcentration of air in the lower region, which counteracts gathering ofcinder products in the lower region. Such an air concentration is alsodesired in cases when air flowing into the furnace should reachcomparatively far into the furnace. According to the prior art, whereair flows in through a slot-like opening arranged on the outside of thefurnace wall around the air port the air flowing in will normally notreach the centre of the furnace, which means that the supply of air tothe combustion will be non-uniform as seen in a cross section of thefurnace and concentrated in the region close to the inner walls of thefurnace.

In the first preferred embodiment of the invention described above theopening 32 has an extension substantially in the vertical direction ofthe drum and the cover member is by that also arranged movable in saiddirection. However, it is within the scope of the claims according tothe invention to have the opening extending substantially in thelongitudinal direction of the drum and according to a further embodimentthe cover member is arranged movable substantially in the longitudinaldirection of the drum.

FIG. 5 illustrates a perspective view of the cleaning arrangementaccording to the invention, which is arranged through the third plate 42mentioned above. The cleaning arrangement 1 comprises, as alreadymentioned, the cleaning member 7, the holding element 8 and the powermember 9. The holding element 8 is through the power member 9reciprocatingly guided in the beam member 33 connected to the plate 42.The cleaning member 7 has resilient properties in at least thetransversal direction of the air port. The cleaning member 7 has alsotwo cleaning elements 10, 11 being resilient with respect to each otherin the transversal direction of the air port. The cleaning elements 10,11 has a shape diverging from the holding element 8 in a restingposition, in which they may be arranged in a position with a smallermutual distance than in the resting position while storing potentialenergy. The cleaning elements are also arranged to store potentialenergy when moving from a position inside the furnace to a position inthe air port. The cleaning elements 10, 11 will by that bear against theinner delimiting walls of the air port when the cleaning member islocated in the air port, and they will carry out a scraping of thedelimiting walls of the air port in the transversal direction when thecleaning member is moved. A very good cleaning of the delimiting wallsof the air port in the transversal direction of the latter is obtainedin this way.

The cleaning member 7 is also intended to have such an extension in thevertical direction of the air port that a scraping of the wallsdelimiting the air port in the vertical direction of the air port alsoare excerted to a cleaning or scraping when moving the cleaning memberwith respect to said limiting walls.

The function of the device according to the invention for cleaning anair port is as follows: Automatically and at predetermined intervals orupon need the power member 9 is controlled by any suitable regulatingassembly to bring the holding element 8 to and fro and the cleaningmember is by that moved to and fro in the air port for removing dustparticles and cinder products from the spent liquor of the furnace fromthe delimiting walls of the air port and from front surfaces facing theinterior of the furnace.

FIGS. 6 and 7 shows the cleaning member 7, when this is located in theair port 3 and inside the furnace, respectively, in which the cleaningmember 7 when located inside the furnace is arranged in a state movedoutwardly through the resilience.

However, the cleaning member may within the scope of the claimsaccording to the invention also have a shape differing from two cleaningelements resilient in the transversal direction of the air port, forexample a sleeve shape.

According to a further embodiment the drum is also air-tightly connectedto the furnace wall 2 around the air port. The drum has in such a caseat least one opening through at least one of the lateral walls thereof.

What is claimed is:
 1. A device for regulating and cleaning an air port(3) arranged in a wall (2) of a furnace, especially a soda housefurnace, comprising a cleaning arrangement (1), which in its turncomprises a cleaning member (7) movable with respect to the walls of theair port (3), and an arrangement (4) for regulating the air flow throughthe air port, an air casing (5) is arranged around the air port on theouter side of the furnace wall, a drum (12) being arranged inside theair casing and connected to a wall (13) of the air casing locatedopposite to the furnace wall, said cleaning arrangement being alsoconnected to said wall of the air casing and extending at leastpartially through the drum, said regulating arrangement having a covermember (14) movable with respect to the drum, said cleaning member beingmovable between two end positions independently of the position of thecover member, and said cleaning member being in a first of the endpositions located at least partially inside the furnace and in a secondof the end positions at least partially outside the furnace,characterized in that the cover member (14) is arranged for regulatingthe air flow through at least one opening (32) defined by at least onelateral wall of the drum (12) and having a restricted extension in thecircumferential direction of the drum.
 2. A device according to claim 1,characterized in that the opening (32) extends over less than half ofthe circumference of the drum (12).
 3. A device according to claim 1characterized in that the opening (32) is arranged close to the air port(3).
 4. A device according to claim 1, characterized in that the covermember (14) has at least one wall portion (30, 31), which is adapted toat least partially cover the opening (32).
 5. A device according toclaim 1, characterized in that the cover member (14) is movablesubstantially in the longitudinal direction of the opening.
 6. A deviceaccording to claim 1, characterized in that the cover member (14) isarranged to be moved along the drum (12) in the longitudinal directionthereof.
 7. A device according to claim 1, characterized in that thedrum (12) has a substantially rectangular cross section.
 8. A deviceaccording to claim 7, characterized in that an end of the drum (12)facing the air port (3) is at least partially arranged at a distancefrom the furnace wall (2) delimiting the air port.
 9. A device accordingto claim 7, characterized in that the cover member (14) is arranged tobe moved substantially in parallel with the furnace wall (2) delimitingthe air port (3).
 10. A device according to claim 7, characterized inthat an upper and a lower wall part (27, 29) having an extension in thetransversal direction of the drum (12) substantially corresponding tothe width of the drum are arranged for connecting the drum at the topand the bottom, respectively, to the air port (3).
 11. A deviceaccording to claim 10, characterized in that the cover member (14) hastwo substantially parallel wall portions (30, 31), which are arranged ata mutual distance corresponding to substantially the width of the drum(12) for at least partially covering the openings (32) formed betweenthe furnace wall (2) delimiting the air port (3), the lateral walls ofthe drum and said wall parts (27, 29) upon movement of the cover member.12. A device according to claim 1, characterized in that also thefurnace wall (2) delimiting the air port (3) is adapted to define saidopening (32).
 13. A device according to claim 1, characterized in thatat least a portion of the opening is arranged on a level with a bottom(37) of the air port (3).
 14. A device according to claim 1,characterized in that the cleaning member (7) has resilient propertiesin at least the transversal direction of the air port (3).
 15. A deviceaccording to claim 14, characterized in that the cleaning member (7) isadapted to store potential energy by bearing against inner walls of theair port upon a movement from a position inside the furnace to aposition in the air port.
 16. A device according to claim 14,characterized in that the cleaning member (7) has a shape diverging inthe direction of the air port towards the furnace.
 17. A deviceaccording to claim 14, characterized in that the cleaning member (7) hastwo cleaning elements (10, 11) resilient with respect to each other inthe transversal direction of the air port (3).
 18. A device according toclaim 1, wherein said cover member (14) is at least partially hollow topermit insertion and retraction of said cleaning member (7) therethrough at all times.
 19. A cleaning arrangement (4) for keeping an airport (3) arranged in a wall (2) of a furnace, especially a soda housefurnace, clean, which comprises a cleaning member (7), a holding element(8) for holding the cleaning member (7) at a first end thereof, and apower member (9), which is actively connected to the holding element (8)at a second end thereof for removing the cleaning member (7) through theholding element (8) with respect to inner walls of the air port (3),said cleaning member (7) being movable between two end positions, andsaid cleaning member structured and arranged to be in a first endposition located at least partially inside the furnace and a second endposition at least partially outside the furnace, characterized in thatthe cleaning member (7) has resilient properties at least in atransverse direction of the air port (3), a beam (33) fixedly mountedupon said powers member (9), with said holding element (8) arranged toreciprocate out from and into said beam member (33), and comprising twocleaning elements (10, 11) mounted upon an end of said holding element(8) opposite said beam (33), said cleaning elements (10,11) beingresilient with respect to each other and in the transverse direction ofthe air port (3), said cleaning elements (10,11) possessing a shapediverging from said holding element (8) in a resting position, in whichsaid cleaning elements (10,11) may be arranged in a position with asmaller mutual distance therebetween than in the resting position, whilestoring a potential energy, and said cleaning elements (10,11) alsobeing arranged to store the potential energy when moving from a positioninside the furnace to a position in the air port (3) such that thecleaning elements (10,11) bear against inner delimiting walls of the airport (3) when the cleaning member (7) is located within the air port(3), and said cleaning elements (10,11) carry out a scraping action toand fro against the delimiting walls of the air port (3) in thetransverse direction when the cleaning member (7) is moved.